JPS5923894B2 - How to manufacture gears from flat plate materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a gear from a flat plate material by plastic deformation.

More specifically, manufacturing a novel spur gear by forming a cup-shaped cylinder with a bottom from a disk-shaped flat plate material obtained by punching or the like from a flat plate material such as a steel plate, and forming tooth profiles on the side surface of the cylinder. The present invention provides a novel gear manufacturing method particularly suitable for manufacturing gears with low meshing surfaces such as timing gears of automobiles. The explanation will be given below using a timing gear as an example.

In the past, gears of this type were usually manufactured by cutting and machining a steel material or by molding a sintered alloy.

The former has the drawback of being extremely expensive to manufacture, while the latter has problems with strength and the wall thickness cannot be lowered below a certain limit, so there are limits to both weight reduction and manufacturing cost. . The present invention establishes a new method for manufacturing gears that solves these problems that could not be solved by the conventional techniques.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a highly productive method for manufacturing inexpensive, lightweight, monolithic gears from plate materials. It is an object of the present invention to provide a lightweight and inexpensive gear manufacturing method that is particularly suitable for gears with relatively low surface pressure at meshing points, or gears with a low tooth height compared to modules. An embodiment of the present invention will be described in detail below.

First, if the material is relatively thin, it is punched out into a circular shape from a continuous flat plate to create the disk material 1, and if it is somewhat thick, it is punched or cut out from a flat plate as shown in Figure 1. A disc material 1 like this is obtained. The disc material 1 is formed into a pot-shaped bottomed cylindrical body 2 by a known drawing process (first step). In this process, the radius of curvature of the corner portion 2a becomes uneven to some extent, and the thickness of the side wall portion 2b becomes slightly uneven. The state after the first step is shown in FIGS. 2 and 2'. In the next step (second step), a known ironing step is carried out to minimize the radius of curvature so that the inner side of the corner portion 2a stands out, and to make the uneven wall thickness of the side wall portion 2b uniform. Add.

The semi-finished product 3 after this second step is approximately in the state shown in FIGS. 3 and 3'. The semi-finished product 3 after the completion of the second process is the side wall portion 3
The wall thickness of b becomes uniform, and the inner side 3a' of the corner portion 3a is formed to have a desired minimum radius of curvature.

There is no need for work hardening to reach this state if the initial material (low carbon steel) is selected. However, of course, depending on the material, an annealing process may be added. In the next step (third step), the semi-finished product 3 is manufactured into a gear having a desired tooth shape 4a by using a female mold 10 and a male mold 11 having tooth shapes 10a and 11a shown in FIG. 6 on the inside and outside, respectively. It is molded into 4. That is, while the semi-finished product 3 is held between the upper stem 12 and the lower stem 13 (the male die 11 is fixed to the upper end), the pressing force of the upper stem 12 causes the gap between the two dies 10 and 11 to be removed. It is pushed out from the void. After the tooth profile 4a shown in FIG. 4' is formed to the desired length in the downward stroke of extrusion, the product is pushed back upwards to be taken out, or the stem 12 is changed and pushed through. The female mold 10 has a guide surface 10c in which the upper end of the tooth profile 10a is inclined downward in order to facilitate deformation of the initial processed portion (lower end 3c) of the workpiece (semi-finished product 3).

The shape of this guide surface may be a conical surface or a morning glory-shaped curved surface.
Therefore, when the semi-finished product 3 descends, after it comes into contact with the guide surface 10c, it is guided by this and forcibly pressed toward the male mold 11, and the male mold 11 and the female mold 10 are separated as shown in FIG.
The material 4 is formed so that the space C between the two is filled with the material 4.
That is, the material filled in the cavity C becomes a gear having a desired tooth profile on the outer surface. In this case, the guide surface 10c forms a raised portion 4c of the tooth profile 4a shown in FIG. 4'.
Furthermore, in this embodiment, it is possible to avoid processing the outer peripheral edge 4e of the upper surface, which is difficult to form, and to prevent the unevenness of the upper surface that tends to appear when cutting the tooth profile to the edge 4e. You may continue until you push it all the way down. Through the above third step, a gear having a tooth profile 4a on its outer circumference and a web 4w having the same thickness as the material 1 is formed as shown in FIG. 4'.

It can be used as a gear immediately by attaching a rotating shaft (not shown) to the center or by drilling a hole for it. Note that, for the purpose of weight reduction, it is desirable to form an appropriate number of lightening holes on the same circumference at equal intervals in the web 4w.

In the case shown in FIGS. 5A and 5B, the deformation 5b of the bottom surface (the inclination of the web 4w, the edging of the relief hole) is further processed from the state shown in FIG. 4 at the same time as the relief hole 5a is punched out. Reference numeral 6 denotes a mounting hole, which is machined for accuracy.

The effect of this embodiment is that a light weight and high strength plate gear can be easily manufactured with a small number of processing steps. Another advantage is that the wall thickness of the product gear becomes uniform. In the above embodiment (first embodiment), the step of making the wall thickness of the side wall uniform described in the second step and the processing step of reducing the radius of curvature of the bent part do not necessarily need to be performed simultaneously, but separately. (Second example).

In the first embodiment, as shown in Fig. 7, the male and female molds for the extrusion process have (10, 11) teeth, which makes the wall thickness of the product almost uniform and reduces the extrusion force. There are advantages to be gained, but on the other hand, it is inevitable that the model will become more complicated.

Therefore, as shown in FIG. 8, it is also possible to make the inner mold (male mold 1V) a simple cylindrical shape and make only the outer mold (female mold 10○) a gear (third embodiment). In this case, the extrusion force becomes large, but the material fills between the extrusion molds 1σ and 11' under high pressure, which has the advantage that it is easy to obtain a product with an accurate tooth profile. Because the first step involves forming a bottomed cylindrical body, it is desirable that the shape of the final gear has a small tooth width compared to the outer diameter of the gear, so it is suitable for applications with relatively small sliding strokes. It is also possible to process splines (fourth embodiment).

Furthermore, if the male and female dies 10 and 11 are chosen to have opposite shapes, it is also possible to process an internal gear (fifth embodiment). Although it is preferable that the gear be an impolite gear, a tooth profile with an arcuate cross section may also be used depending on the application. Further, the material is not limited to steel, but may also be non-ferrous metal or plastic. To summarize the effects of the present invention that are common to each embodiment, gears can be efficiently manufactured from a flat disc-shaped material by non-cutting plastic deformation and through a relatively small number of steps. Moreover, the obtained product is dense, lightweight, and strong.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the raw material, Figure 2 is a cross-sectional view of an intermediate product obtained by drawing the image in Figure 1, Figure 3 is a cross-sectional view of a semi-finished product obtained by cutting the image in Figure 2, and Figure 4 is a cross-sectional view of the semi-finished product obtained by drawing the image in Figure 1. FIG. 4 is a cross-sectional view of the outer surface of FIG. 3 with tooth-shaped molding. Figures 2', 3' and 4' are enlarged views of the main parts of Figures 2, 3 and 4, respectively. FIG. 5A is a sectional view showing a final stage product according to the method of the present invention, and FIG. 5B is a bottom view thereof (viewed from -V in FIG. 5A). FIG. 6 is a sectional view of essential parts of a die and press device for forming the tooth profile shown in FIG. 4'. FIG. 7 is an enlarged view of the - cross-sectional main part of FIG. 6 during extrusion processing. FIG. 8 is a sectional view showing another embodiment of FIG. 7. 1: Disk-shaped material, 2: Semi-finished product drawn at 1 (pot-shaped product), 3: Semi-finished product with 2 edges, 4: Semi-finished product with teeth formed on the outside of 3, 5: Final product An example (timing gear), 6: Mounting hole (5), 1
0...Female type, 11: Male type, 12: Stem (for pressure), 13: Stem (for support).

Claims (1)

[Scope of Claims] 1. A method for manufacturing a gear from a flat plate material, characterized by including the following steps. (a) Drawing step of forming a bottomed cylindrical body from a disc-shaped flat plate material. (b) A shaping step in which the radius of curvature of the bent portion of the cylindrical body is reduced at the same time or before or after making the side wall thickness of the cylindrical body uniform. (c) An extrusion step in which a tooth profile is formed on the side wall surface of the cylindrical body after the above two steps (a) and (b).